Histone Deacetylase Inhibition: A Novel Approach to Cardioprotection

描述(由申请人提供)：尽管有多项重大的治疗进展，心肌梗死仍是心血管疾病的主要原因。心肌缺血/再灌注损伤仍是一个尚未解决的主要问题。组蛋白乙酰转移酶(HAT)和组蛋白脱乙酰基酶(HDAC)是通过调节染色质结构来调节基因表达的酶。它们也以非组蛋白蛋白为靶标，代表了生物信号传递的一般调控机制。HDAC抑制剂已被证明是有效的抗癌药物，并正在成为针对实体和血液系统恶性肿瘤的令人兴奋的临床治疗方法。抑制HDAC可钝化心肌肥厚。我们的研究表明，抑制HDAC对小鼠急性心肌缺血和心肌梗死具有心脏保护作用。HDAC抑制导致小鼠心脏中p38和MKK3的乙酰化和激活。我们已经确定p38在赖氨酸53和121位发生乙酰化。我们还证明，HDAC抑制导致慢性心肌梗死患者c-kit干细胞、细胞增殖和有丝分裂增加。然而，HDAC抑制保护心脏免受损伤的机制(S)仍不清楚。我们的工作假设是，HDAC抑制通过激活MKK3和p38来保护心脏免受心肌损伤。我们进一步假设，HDAC抑制的保护作用与预防心肌重塑和增加心肌梗死后新形成的心脏成分有关。利用遗传学和生理学方法，我们将测试：特定目标1：检测急性心肌缺血、缺血/再灌注和慢性心肌梗死的HDAC活性和HDAC 3、4和5：我们将检测急性心肌缺血、缺血/再灌注和慢性心肌梗死时缺血心肌的HDAC活性。我们将研究HDAC3、4和5蛋白及其在上述两种环境中的亚细胞分布。特异性目的2：探讨MKK3、p38和Akt1信号通路在hDAC抑制所致的心肌保护中的作用：以p38上游激活剂MKK3缺失、心脏p38消除和p38药物抑制的小鼠为研究对象，确定mKK3和p38抑制是否会消除hDAC抑制的心脏保护作用(S)。具体目标3：利用体外分析和细胞培养模型破译p38激活的分子机制(S)：利用建立的体外和细胞培养模型，我们将表征p38的乙酰化以及这种翻译后修饰对p38活性的调节。具体目的4：探讨HDAC抑制是否与慢性心肌梗死后的心肌修复有关。研究HDAC抑制在缺血性心脏中的作用，不仅可以为我们理解心血管生物学提供新的视角，而且可以为缺血性心脏病和其他心血管疾病患者的治疗策略的发展提供新的思路。公共卫生相关性：该项目不仅为我们理解HDAC抑制保护缺血性心脏的新机制提供了新的见解，而且也为缺血性心脏病和其他心血管疾病患者开发治疗策略提供了希望。

DESCRIPTION (provided by applicant): Myocardial infarction contributes a major reason for cardiovascular disease despite the multiple significant therapeutic advances. Myocardial ischemia/reperfusion injury is still a major unsolved problem. Histone acetyltransferases (HAT) and histone deacetylases (HDAC) are enzymes that modify the expression of genes by regulating chromatin structure. They also target non-histone protein and represent a general regulatory mechanism in biological signaling. HDAC inhibitors have shown efficacy as anti-cancer drugs and are emerging as exciting clinical treatments targeting solid and hematological malignancies. HDAC inhibition blunts cardiac hypertrophy. Our studies have shown that HDAC inhibition is associated with cardioprotection in acute myocardial ischemia and myocardial infarction in mouse. HDAC inhibition results in the acetylation and activation of both p38 and MKK3 in mouse hearts. We have identified that p38 is acetylated at lysine 53 and lysine 121 sites. We also demonstrated that HDAC inhibition resulted in an increase in c-kit stem cells, cell proliferation and mitosis in chronic infarcted hearts. However, the mechanism(s) by which HDAC inhibition protects the heart against injury remain unknown. Our working hypothesis is that HDAC inhibition protects the heart against myocardial injury through the activation of MKK3 and p38. We further hypothesize that the protection of HDAC inhibition is related to prevention of myocardial remodeling and an increase in newly formed cardiac components following myocardial infarction. Utilizing genetic and physiological approaches, we will test: Specific Aim 1: Examine HDAC activity and HDAC 3, 4 and 5 in acute myocardial ischemia, ischemia/reperfusion and chronic myocardial infarction: We will measure HDAC activity in ischemic myocardium in both acute ischemia, ischemia/reperfusion and chronic myocardial infarction. We will examine HDAC 3, 4 and 5 proteins and their subcellular distributions in both settings above. Specific Aim 2: Assess the roles of MKK3, p38 and Akt1 signaling pathway in the cardioprotection induced by HDAC inhibition: Using mice with deletion of MKK3, the upstream activator of p38, elimination of cardiac p38 and pharmacologic inhibition of p38, we will determine whether inhibition of MKK3 and p38 will abrogate the cardioprotective effect(s) of HDAC inhibition. Specific Aim 3: Decipher the molecular mechanism (s) of p38 activation using in vitro analysis and cell culture models: Using established the in vitro and cell culture model, we will characterize the acetylation of p38 and that such a post-translational modification will regulate p38 activity. Specific Aim 4: Explore whether HDAC inhibition is associated with myocardial repair following chronic myocardial infarction. Investigating the role of HDAC inhibition in ischemic heart could provide not only new insight into our understanding of cardiovascular biology but also development of therapeutic strategies for patients with ischemic heart disease and other cardiovascular disorders. PUBLIC HEALTH RELEVANCE: This project not only provides a new insight into our understand a novel mechanism by which HDAC inhibition protects ischemic heart, but it also holds promise to develop a therapeutic strategy for patients with ischemic heart diseases and other cardiovascular disorders.